The veteran backbencher's agenda includes renationalising railways and energy companies, reversing spending cuts and a large-scale housebuilding programme – which would come with an astronomical price tag of £42 million.

Now a senior Tory minister has slammed Corbyn, the odds-on frontrunner to succeed Ed Miliband, as "anti-aspirational, anti-worker" and a "damaging throwback" – and said that hardworking Britons face tax hikes under a "Back to the Future Labour Party".

Conservatives have also claimed that families would face eye-watering tax hikes under a government led by any of the four Labour leadership contenders.

Their figures show shadow health secretary Andy Burnham's manifesto – which also includes taxpayers footing the bill for taking the rail network back into public ownership – would add £1,409 to a family's annual tax bill.

It also indicates shadow home secretary Yvette Cooper's pledges would increase each British household's financial burden by £1,385, and Blairite Liz Kendall's policies would cost families over £1,000 a year.

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Conservative Cabinet Office minister Matthew Hancock criticised the Labour candidates' plans for "more welfare spending, more borrowing and more taxes" and suggested the party had not learnt its lesson from its role in the financial crash.

He said: "No matter who ends up in charge we have a Back to the Future Labour Party with every candidate wanting to take Britain for a ride back in time through more welfare spending, more borrowing and more taxes - which is exactly how they got us into a mess last time.

"Unsurprisingly the most anti-aspirational, anti-worker and damaging throwback of the lot - Jeremy Corbyn - has pledged to spend the most.

“Like most antiques his unfunded policies don't come cheap and a Corbyn premiership comes with a £42 billion price-tag which amounts to £2,400 for every working household.”

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Blair has been an outspoken critic of Corbyn's rise

If Jeremy Corbyn becomes leader it won't be a defeat like 1983 or 2015 at the next election. It will mean a rout, possibly annihilation.

Tony Blair

Corbyn's straight-talking brand of old-school socialist politics has seen him win massive support from the Labour grassroots – but grandees in the party like ex-PM Tony Blair have warned that he would lead the party to "annihilation".

Blair made his second intervention into the leadership race this week, having earlier told supporters of Corbyn to "get a transplant" if their heart was with the Islington North MP.

Writing for the Guardian, he said: "The party is walking eyes shut, arms outstretched over the cliff's edge to the jagged rocks below.

"If Jeremy Corbyn becomes leader it won't be a defeat like 1983 or 2015 at the next election. It will mean a rout, possibly annihilation."

A shock YouGov poll released earlier this week showed Corbyn winning the leadership in the first round of voting with a whopping 53 per cent of the vote.

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Yvette Cooper has hit out at Corbyn

His runaway success yesterday prompted an intervention from Yvette Cooper, who claimed his politics "aren't radical and aren't credible".

The shadow home secretary said: "I understand Jeremy has strong support but his answers are the wrong answers for the future.

"They won't change the world, they will keep us out of power and stop us changing the world."

Although he is on course to win the leadership next month, Corbyn – who was initially a 100/1 no-hoper with bookmakers – has come under fire for his links to terrorist groups over the course of the campaign.

Last week he refused five times to condemn the terrorist attacks of the IRA – and he clashed with Channel 4 News host Krishnan Guru-Murthy over allegations he called Islamist terrorists Hamas and Hezbollah his "friends".